Question 1122925
{{{system(60/x+180/y=10,180/x+60/y=8&2/3)}}}


{{{system(X=1/x, Y=1/y)}}}


Substitute the new variables.

{{{system(60X+180Y=10,180X+60Y=8&2/3)}}}


{{{system(180X+540Y=30,180X+60Y=8&2/3)}}}


{{{480Y=21&1/3}}}


{{{Y=(21&1/3)/480}}}


Back-substitute:    {{{y=480/21&1/3}}}


  {{{highlight(y=22&1/2)}}}------speed for second part of journey


{{{highlight(x=30)}}}-------speed for first part of journey